Harshavardhana <******@****.***> 1699046298 -0700

# Decommissioning

Decommissiong is a mechanism in MinIO to drain older pools (usually with old hardware) and migrate the content from such pools to a newer pools (usually better hardware). Decommissioning spreads the data across all pools - for example, if you decommission `pool1`, all the data from `pool1` spreads across `pool2` and `pool3`.

## Features

	}

	var nmeta1 poolMeta
	nmeta1.Version = poolMetaVersion
	nmeta1.Pools = append(nmeta1.Pools, meta.Pools...)
	for i, pool := range nmeta1.Pools {
		if i == 0 {
			nmeta1.Pools[i] = PoolStatus{
				CmdLine:    pool.CmdLine,
				ID:         i,
				LastUpdate: UTCNow(),
				Decommission: &PoolDecommissionInfo{
					Complete: true,
				},
			}
		}
	}

	var nmeta2 poolMeta
	nmeta2.Version = poolMetaVersion

		}
		if !ps.Participating {
			continue
		}
		// for participating pools, total bytes to be rebalanced by this pool is given by,
		// pf_c = (f_i + x)/c_i,
		// pf_c - percentage free space across pools, f_i - ith pool's free space, c_i - ith pool's capacity
		// i.e. x = c_i*pfc -f_i
		totalBytesToRebal := float64(ps.InitCapacity)*meta.PercentFreeGoal - float64(ps.InitFreeSpace)
		elapsed := time.Since(ps.Info.StartTime)

console-address: ':9001'
certs-dir: '/home/user/.minio/certs/'
pools: # Specify the nodes and drives with pools
  -
        - 'https://server-example-pool1:9000/mnt/disk{1...4}/'
        - 'https://server1-pool1:9000/mnt/disk{1...4}/'
        - 'https://server3-pool1:9000/mnt/disk{1...4}/'
        - 'https://server4-pool1:9000/mnt/disk{1...4}/'
  -
        - 'https://server-example-pool2:9000/mnt/disk{1...4}/'

`v1` format
```yaml
pools: # Specify the nodes and drives with pools
  -
    - "https://server-example-pool1:9000/mnt/disk{1...4}/"
    - "https://server{1...2}-pool1:9000/mnt/disk{1...4}/"
    - "https://server3-pool1:9000/mnt/disk{1...4}/"
    - "https://server4-pool1:9000/mnt/disk{1...4}/"
```

to `v2` format

```yaml
pools:
  - args:

console-address: ':9001'
certs-dir: '/home/user/.minio/certs/'
pools: # Specify the nodes and drives with pools
  -
        - 'https://server-example-pool1:9000/mnt/disk{1...4}/'
        - 'https://server{1...2}-pool1:9000/mnt/disk{1...4}/'
        - 'https://server3-pool1:9000/mnt/disk{1...4}/'
        - 'https://server4-pool1:9000/mnt/disk{1...4}/'
  -
        - 'https://server-example-pool2:9000/mnt/disk{1...4}/'

console-address: ':9001'
certs-dir: '/home/user/.minio/certs/'
pools: # Specify the nodes and drives with pools
  -
        - 'https://server-example-pool1:9000/mnt/disk{1...4}/'
        - 'https://server1-pool1:9000/mnt/disk{1...4}/'
        - 'https://server3-pool1:9000/mnt/disk{1...4}/'
        - 'https://server4-pool1:9000/mnt/disk{1...4}/'
  -
        - 'https://server-example-pool2:9000/mnt/disk{1...4}/'

				t.Error("expected success, got failure", err)
			}
			if err == nil {
				if len(sctx.Layout.pools) != 2 {
					t.Error("expected parsed pools to be 2, not", len(sctx.Layout.pools))
				}
				if sctx.Layout.pools[0].cmdline != testcase.hash {
					t.Error("expected hash", testcase.hash, "got", sctx.Layout.pools[0].cmdline)
				}
			}
		})
	}
}

// Tests initializing new object layer.

- MinIO also supports expansion of existing clusters in server pools. Each pool is a self contained entity with same SLA's (read/write quorum) for each object as original cluster. By using the existing namespace for lookup validation MinIO ensures conflicting objects are not created. When no such object exists then MinIO simply uses the least used pool to place new objects.

### There are no limits on how many server pools can be combined

```